This invention relates to an enclosed switchgear in which circuit breaker chambers and conductors interconnecting these chambers are arranged in a simplified manner.
Among enclosed type switchgears (hereinafter termed power receiving switchgears), there is, for instance, a switchgear as shown in a single line diagram such as shown in FIG. 1, which receives electric power from two separate power line systems. As shown in FIG. 1, the secondary winding of a first power line transformer 1, the primary or high-voltage winding of which is connected to the first power line system, is connected through a current transformer (CT) 2, an air circuit breaker (ACB) 3 and current transformers (CT) 2 and 2a to one terminal of a bus tie air circuit breaker (ACB) 4, all encased in the power receiving switchgear which is indicated by one dot dash line. Likewise, the secondary winding of a second power line transformer 5, the primary or high-voltage winding of which is connected to the second power line system, is connected through a current transformer (CT) 2, air circuit breaker (ACB) 6, and current transformers (CT) 2 and 2a to the other terminal of the air circuit breaker (ACB) 4, also encased in the power receiving switchgear. Potential transformers (PT) 7 are connected to the power source side terminals of the ACBs 3 and 6, and also to both side terminals of the ACB 4. The load side terminals of the ACBs 3 and 6 of the power receiving switchgear are ordinarily connected to feeder circuit breakers (ACBF)8a, 8b and 9a, 9b, respectively, as shown by dash lines.
FIG. 2 is a diagram showing the arrangement of the above described components of the power receiving switchgear. In FIG. 2, the switchgear indicated by a solid line comprises a first power receiving panel 11 provided on the left side, a second power receiving panel 12 provided on the right side, and a bus tie panel 13 provided at the center. Feeder panels 14 and 15 are arranged on the left side and right side of the switchgear as indicated by one-dot dash lines. Each of the panels is divided vertically into three chambers, so that the entire power receiving switchgear includes 9 unit chambers comprising PT unit chambers 11a, 12a, 13a, 13c, circuit breaker unit chambers 11b, 12b, 13b and empty unit chambers 11c and 12c. In the intermediate stage of the first power receiving panel 11 is provided a circuit breaker chamber encasing the ACB 3, while in the intermediate stage of the second power receiving panel 12, there is provided a circuit breaker chamber encasing the ACB 6. In the intermediate stage of the bus tie panel 13, another circuit breaker chamber encasing the ACB 4 is provided. In each of the feeder panels 14 and 15, circuit breaker chambers are provided in the intermediate stage and the lower stage. Potential transformers (PT) 7 are, provided in the upper stage of the first and second power receiving panels 11 and 12, and in the upper and lower stages of the bus tie panel 13, respectively. The conductors connected to the air circuit breakers encased in the circuit breaker chambers are provided, together with the CTs, in a bus chamber provided on the rear side of the power receiving switchgear.
FIG. 3 is a perspective view showing the bus chamber provided on the rear side of the switchgear. In FIG. 3, the lower ends of conductors 111 connected to the secondary windings of the transformer 1, that receives electric power from the first power line system, are connected with the rear ends of conductors 112 provided on the rear side of the ACB 3, not shown in FIG. 3. The forward ends of the conductors 112 are connected to the upper terminals of the ACB 3. The lower terminals of the ACB 3 are connected to the forward ends of L-shaped conductors 113, the rightward ends of which are connected to intermediate portions of vertically disposed conductors 114. The lower ends of the conductors 114 (see FIG. 4) are connected with the right ends of horizontally disposed conductors 115. The left ends of the conductors 115 are connected to the lower ends of vertically disposed conductors 118 through connecting pieces 116 and 117. The upper ends of the conductors 118 are connected with the right ends of L-shaped conductors 119, the forward ends of which are connected to the lower terminals of the ACB 4, not shown in FIG. 3.
In the same manner, the lower ends of conductors 121, the upper ends of which are connected to the secondary windings of the transformer 5 that receives electric power from the second power line system are connected with the rear ends of conductors 122 disposed forwardly, the forward ends of the conductors 122 being connected to the upper terminals of the ACB 6, not shown in FIG. 3. The lower terminals of the ACB 6 are connected with the forward ends of substantially L-shaped conductors 123, the right ends of which are connected to the lower parts of vertically disposed conductors 124 (see FIG. 4). The upper ends of the conductors 124 are connected through connecting pieces 125 and 126 and conductors 127 to the upper ends of conductors 128 disposed vertically. The lower ends of the conductors 128 are connected to the right ends of substantially L-shaped conductors 129, the forward ends of which are connected to the upper terminals of the ACB 4. The upper ends of the vertical conductors 124 are further connected with the right ends of horizontally disposed conductors 130.
The arrangement of the conductors in bus chambers provided on the rear side of the feeder panels 14 and 15, which are arranged on both sides of the power receiving switchgear, is also indicated in FIG. 3. In the bus chamber provided on the rear side of the feeder panel 14, the left ends of horizontal conductors 141 are connected with the upper ends of the vertical conductors 114, which are connected through the conductors 113, 115, 116, 117, 118 and 119 to the lower terminals of the ACBs 3 and 4. The right ends of the conductors 141 are connected with the upper ends of vertically disposed conductors 142. Right ends of substantially L-shaped conductors 143 and 144 are connected to intermediate portions and the lower ends of the conductors 142. The forward ends of the L-shaped conductors 143 and 144 are connected to the upper terminals of ACBF 8a and ACBF 8b, not shown in FIG. 3, which are provided in the circuit breaker chamber of the feeder panel 14. The lower terminals of the ACBF 8a and ACBF 8b are connected with the forward ends of load side conductors 145 and 146, the rear ends of which are connected with terminal plates 147, respectively.
Likewise, in the bus chamber on the rear side of the feeder panel 15 provided on the left side of the switchgear, the upper ends of vertical conductors 151 are connected to the left ends of the horizontal disposed conductors 130 which are provided in the bus chamber formed on the rear side of the second power receiving panel 12. The right ends of substantially L-shaped conductors 152 and 153 are connected to intermediate portions and lower ends of the vertical conductors 151, respectively. The forward ends of the conductors 152 and 153 are connected to the upper terminals of the feeder circuit breakers ACBF 9a and ACBF 9b, respectively. The forward ends of load side conductors 154 and 155 are connected to the lower terminals of the feeder circuit breakers ACBF 9a and ACBF 9b, respectively, and the rear ends of the load side conductors 154 and 155 are connected with terminal plates 156.
FIG. 4 is a perspective view showing merely T-phase conductors. In FIG. 4, conductors indicated by solid lines are provided within the bus chamber of the power receiving switchgear, while the conductors indicated by dot and dash lines are those provided in the bus chambers of the feeder panels (for simplicity, the load side conductors and the terminal plates provided therein are omitted). As is apparent from FIG. 4, the bus chamber of the power receiving switchgear includes 19 conductors per one phase, that is 57 conductors for three phases.
It has been found that the above described construction of the conventional power receiving switchgear gives rise to following difficulties.
(1) Since, three circuit breakers are encased in three panels, respectively, a large floor area is required for the installation of the switchgear.
(2) Since a large number of units (9 units) are required for encasing the component elements, the manufacture of the box-shaped structure of the switchgear requires a long time fabrication, and furthermore, the increasing of the kind of units requires troublesome assembling of the switchgear.
(3) In the three circuit breaker chambers arranged in a juxtaposed relation, since the upper terminals of a circuit breaker are connected to the lower terminals of another circuit breaker, the number of vertical conductors inevitably increases, thus complicating the arrangement and increasing the numbers, kinds and lengths of the conductors.
(4) Since the number of the conductors increases, the connecting points therebetween also increase. Furthermore, since the length of the conductors becomes long, the amount of heat thereby created increases, thereby causing high temperature rise.
(5) Since the number and kind of the conductors thus increased, the manufacture of the conductors and the assembling of the same become troublesome.
(6) Since the construction and the arrangement of the conductors are complicated, the inspection and maintenance of the switchgear also become troublesome.